Update README.md

# vi commands.cfg

## Check Mysql Replication
define command{
    command_name    check_mysql_slave
    command_line    $USER1$/check_slave.sh -h $HOSTADDRESS$
}

OR

## Check Mysql Replication
define command{
    command_name    check_mysql_slave
    command_line    $USER1$/check_slave.sh -u ptcheck -p yangcan -h $HOSTADDRESS$ -P $ARG1$
}


## 在服务中添加监控
# vi localhost.cfg

define service{
        use                             general-service
        host_name                       127.0.0.1
        service_description             Server - Mysql Replication
        check_command                   check_mysql_slave
        }
        
OR

define service{
        use                             general-service
        host_name                       127.0.0.1
        service_description             Server - Mysql Replication
        check_command                   check_mysql_slave!3308
        }